Machine for finishing gears



March l5, 1938. R. s. coNDoN n MACHINE FOR FINI-SHING GARS 11sheets-sheet 1 Filed Sept. lO, 1935 Srwentor 'ef/ J @2M/a' GttornegMACHINE FOR FI NISH1NG GEARS Filed Sept. 10, 1935 11 Sheets-Sheet 2Bnnentor by? afm/W l Gttorneg March 15, 1938. R. s. CONDON- MACHINE FORFINISHING GEARS 1l Sheets-Sheet 5 Filed Sepb. l0, 1935 hl, NN MMM. Nw mwww m QJ N, ww N QS bmw @nw @N v. U7 /\\f www* .r lwlmmmwllllvlll: 1- mCttorneg March 15, 1938. R. s. coNDoN 2,111,170

vMACHINE FOR FINsHlNG GEARS Filed Sept. 10, 1955 l 11 sheets-Sheet 4mm)- \Q\% NN km, N wr/ww, www uw a y l -i i -4 n----l,--}-ll-|l ---i mI\-Tl www {VWG} -L m v N mn NS@ SQ @W g@ Mara. 15, 1938.. R s. CONDON2,111,170

MACHINE FOR FINISHING GEARS F11ed sept. 1o, 1955 11 sheefs-sheet 5Snnentor March15,.1938. RSCOWON www MACHINE FOR FINISHING GEARS FiledSept. l0, 1935 l1 Sheets-Sheet 6 Zmventor im@ f Cttorneg March l5, 1938.Rfs. coNDoN MACHIANE FOR FINISHING- GEARS Filed sept. 10, 1935- 11Sheets-SheefI 7 wy- QQ Q h QN RN Nw ff, um j (ttorneg .W 15, 1938. R.sncoNDloN v H3170 lMACHINE FOR FINISHING GEARS Filed sept. 1o, 1955 11sheetfsfsheet's I f// J @add/gum Gftorneg March l5,` 1938. R. s. coNDoN2,111,170

MACHINE FOR-FINI5H1NG GEARS Filed Sept. l0, 1955 11 Sheets-Sheet 9 March15, 11938.'

R. S. CONDON MACHINE FOR FINISHING GEARS Fi'led Sept. l0, 1935 llSheets-Sheet l0 f F" f y' Smaentor mtomeg March 15, 1938. R. s. coNDoN2,111,170

I MACHINE FOR FINISHING'GEARS Filed sept. 1o, 1955 11 sheets-sheet 11#for mommy Patented Mar. 15, 1938 PATENT OFFICE 2,111,170 MACHINE FORFINISHING GEARS 'Robert s. condon, menester, N.

Gleason Works, Rochester, N. Y.,

of New York A l -22 claims. The present invention relates to machinesfor finishing and testing gears, particularly to machines of thecombination type for lapping and testing or burnishing and testinggears. In a 6 4more specific aspect, the invention relates to ma,

chines for lapping or burnishing and testing .spiral bevel and hypoidgears.

One of the principal objects of this invention is lto provide anautomatic machine for lapping 10 and burnishing spiral bevel and hypoidgears,

which will operate according to the basic principles of the U. S. patent'ci' Alton P. Slade, No.V

1,796,484 of March 17,V 1931 and which will be of simpliiled andimproved construction as -coml5 pared with. the automatic machine or thejoint U. S.'patent of myself, E. W. Bullock and. Eyvind v Finsen, No.1,881,999 of October 11, 1932.

StillA another object of the invention is to provide a machine ofthetype in which the relative positions of the meshing gears are. changedduring lapping in order to effect the lapping operae tion and to obtaina suitable' localization ol tooth bearing, in which the amount ofback-lash between the gears may be controlled and, if desired,

maintained substantially constant `throughout lapping. a

, Another object of the invention is to provide a gear burnishing orlapping'machine in which the lapping or burnishing operations onopposite Sil-'sides of the teeth can be eiected at different rates.Still another object ofthe invention is tc provide in a combinedburnishing or lapping and testing machine, improved `means for bothprotecting the operatoragainst injury and preventing damage to the gearsbeing-burnished, lapped or tested;

Other objectsof the invention will be apparent hereinafter from thespecification and from the v 10 recital of the appended claims.

in the machines' of the type described in Patent Nos. 1,796,484 and1,881,999, lapping or burnishing of a pair of spiral bevel or hypoidgears is accomplished by rotating the pair of gears to 4 5 be lapped orburnished in mesh land simultaneously moving one ofthe gears indirections both longitudinal of the axis of the other gear andtransversely thereof.- A

In burnishing, theteeth of one gear are bot- 50 tomedin the tooth spacesof the other and are held in engagement by spring pressure and as theone gear moves longitudinally and transversely of the other gear, thesprings yield and cramping of the teeth of the gears is avoided. 56 Inlapping, however, it-is not desirable to mesh gear. This has meant, ofcourse,

jthe gears will be more cordingly the lapping a'ction will be reduced.-

should be oscillated Y., assignor a corpi'iration4 y 'Applicationseptember 1o, 1935, sensi No. 39,952

the gears so that the teeth. of one bottom in the tooth spaces of theother.

It has been necessary heretofore, then, to set up the gears withsumcient back-lash to avoid interference at the ends of the teeth as onegear moves first toward the small end and then toward the larger end ofthe teeth oi' the other that in the centrai position, the. amount ofback-lash between than necessary'- and ac- In the machine of the presentinvention, provision is made for mechanically and-automatical-l lymaintaining a uniform amount of back-lash between the gears duringlappingin all positions of their relative movemen Thus the mosteffective lapping action can be obtained throughout the whole of thelapping operation and .therefore the speed of the lapping operation canbe increased.

. In the machines of both the patents mentioned, the relativelongitudinal and transverse movementsbetween the meshing gears areeffected by oscillation of a carrier in which one of the gears iseccentrically mounted. This same construction is retained in the presentmachine. In order/ to obtain the desired tooth bearing on oppositesidesv 'of the teeth, practice has demonstrated that`it isdesirabletorunthe meshinggears together nrst in one direction and then in the otherand that during rotation in opposite directions, the carrier throughdierent angles and -at diierent rates. This is becayse of the difterencein the eiects' of lapping or burnishing on the drive and coast sides ofthegear teeth.

In the machines of both prior patents mentioned, two different cams wereemployed to produce the diering oscillating motions required` -for theburnishing or lapping of the opposite oscillating motion of the gearcarrier, and then at the end of a given period-the machine'was stopped.In the burnishing or lapping of either side of the gear teeth, thecarrier-control cam made one or more revolutions and hence in thelapping or burnishing of the two sides of the teeth, the cam shaft madea plurality of revolutions. Hence, it was necessary in both priormachines to employ an automatic stopping mechanism having a counterarrangement to stop the machine when the lapping or burnishing operationwas completed.

In the preferred embodiment of the present invention, a single'cam isemployed to control the oscillating motions of thecarrier in thefinishing of both sides of the gear teeth. One-half of this cam controlsthe oscillating motion of the carrier during finishing of the drive sideof the teeth and the other half of the cam controls the motion of thecarrier during finishing of the coast side 0f the teeth. It is notnecessary to shift from one cam to another between the operations on theopposite sides of the teeth. Moreover, in a single revolution of the camshaft, theY whole cycle ofoperation of the machine is completed.

Hence the expensive automatic stopping mecha- In the embodiment of theinvention illustrated.

i in the drawings, the gear spindle is journaled in a sleeve or quillwhich is axially movable in the oscillatable carrier. For lapping, thissleeve is moved axially to maintain a controlled amount of back-lash byoscillation of a screw which threads into a nut that is secured to thesleeve. This provides a very simple, compact construction. Forburnishing, the screw and nut are omitted but the' gears are held inmesh with the teeth of one bottoming in the tooth spaces of the other bycoil-springs which operate directly upon the quilior sleeve. Thisconstitutes an improvement in burnishing machine construction,becausethe springs are able to act more directly upon the gears than inthe prior machines, and there` is less likelihood of vibration orchatter.

A further improvement of the present machine particularly valuable forlapping, is an improved back-lash brake. This is inthe form of ahydraulic pump driven from the gear spindle. The pump forms part ofanopen hydraulic system-and is connected to a sump so that when the pumpis in operation, it will pump liquid outAof the sump `and discharge itback into the sump again. The amount of load or resistance to be appliedto the gears is determined by the setting oi a relief valve whichcontrols the discharge from the pump. -The greater the liquid pressurerequired to open the relief valve,fthe greater the resistance to theturning of the pump and, therefore, the greater the resistance to therotation of the gears, that is, the greater the load applied to them.This type of brake has been found very much more satisfactory than thefriction type of brake used on vprevious machines. Friction brakes areliable to wear and if oil or grease get on the friction surface,slippage, or grabbing will occur. The lapping of gears is a precisionoperation and the improvement in the back-lash brake makes possible amore accurate product.

As indicate invention ma be used forI lapping or burnishing and testing.For testing, the gears are simply run together on center and nooscillating or axial Yout of operative position.

above, then/machine of the pres-ent motions are employed. A guard is, ofcourse, provided on the machine to enclose the gears during lapping orburnishing.` Safety features have been incorporated in the electricalcircuit of the machine so that for lapping, the guard must be closed andthe oscillating cam must be in operating position while `for testing,the guard must be open and the yoscillating cam must be As a furthersafety feature, to prevent any possibility of the operator getting'hishands caught` between the gears, during testing, provision is made sothat the operator must keep one hand on a push button during the wholeof the test in order to keep the machine running. His other hand, ofcourse. will be out of the yway as it will be operating a hand brake toapply the load required to test the gears.

In the drawings:

Fig. '1 is the side elevation, with parts broken away, of a combinationburnishing or lapping and testing machine constructed according to thepresent invention; s

Fig. 2 is a plan yview of this machine;

Fig. 3 is a longitudinal sectional view of` the motions to the carrierand quill, respectively, in

the lapping machine;

Fig. '7 is a section approximatelyon the line l-1 of Fig. 5, showing thecam shaft and details y Aof the drive therefor;

Fig. 8 is a sectional view taken approximately on the line 8 8 of Fig.7;

Fig. 9 is a view looking at the end of the gear l head and showing thehydraulic back-lash braking mechanism; i

Fig. 10 is a developedsectional view on the line Illl0 of Fig. 9;

Fig. 11 is a sectional view on the line H--I l of Fig. 9;

Fig. 12 is a fragmentary sectional viewshowing g1 detail the mechanismfor adjusting the pinion Fig. 13 is a sectional view of the lappingguard, showing the piping for conducting the lapping compound on to thegears and the limit switch which insures that the guard is closed duringa lapping or burnishing operation;

Fig. 14.- is a fragmentary view taken at right angles to' Fig. 13 Iandshowing details ofthe distributing system for lthe lapping compound;

Figures 15 and 16 are side elevational views of typical cams forcontrolling the oscillating and axial movements of the carrier andquill, respectively;

Fig. 17 is a fragmentary sectional view on the line I'i-Il of Figure';

. Fig. 18 is a fragmentary sectional view on the line |8-l8 of Fig. '7:f

l JFigures 19A to 24 inclusive are diagrammatic views illustrating howinterference will occur during lapping at the ends of the teeth of themeshinggears in the shifting movements of -one mounted, as in previousmachines, a head 3| and' burnished," lapped or tested,

detail here. The pinion spindle 36 is'driven from.

the head 46 on the column 32 may be the same spindle 48 ismountedeccentrially in the carrier. 'Ihe carrier is journaled in 'plainbearings 5 4 and..

Fig. 25 is anelectrical wiring diagram. of the machine. s

Referring now to the drawings by numerals of reference, designates thebase or frame of the machine. On this base or frame there are a column32 (Figures 1, 2, and 5). These are adjustable on the base or frame atright angles to one another to bring the gears to be lapped, burnished,or tested into meshing engagement.

Journaled in anti-friction bearings 34 and 35 in'thehead 3| is thedrive-spindle 36 of the machine. The pinion of the pair of gears'to be Yor if a special burnishing or lapping pinion is used, that pinion, issecured to the drive-spindle 36. Any suitable chucking mechanism may beemployed for securing the pinion to the drive-spindle. In the ma.-

chine illustrated, a hydraulic chucking mecha.-

nism, designated as a whole at 38 is employed for this purpose. is ofstandardv construction and forms no partof the present invention, itwill not be described in a motor 40 mountd in the base of the machinethrough pulleys 4| and 4 2fand the belting 43 connecting the same.

The column 32 is provided with vertical ways (Figs. 5 and 7) on whichthe gear head 46 is vertically adjustable. The means for adjusting asemployed in the machine-oi. Patent No.

1,881,999-and for that reason will not further be described here.

The gear or driven spindle 48 of the machine is carried in this gearhead 46. `It is iournaled on anti-friction bearings 49. and 50 in asleeve or quill 5| and this quill is slidably mounted in an oscillatablecarrier 52 (Figs. 3 and 5). lThe mounting of the spindle 48 in the quill5| and of the quill 5| in the carrier 52 is such that the laxis of thespindle 48 is offset fromthe axis of the carrier but parallel thereto,'that is, that 55 formed integral with the head 46.

The gear G to be burnished, lapped ortested or, in case a specialburnishing or lapping.,gear is used, that gear, is secured to the drivenspindle 48. For securing the gear to the spindle, any suitable type ofchucking mechanism may be employed. In the machine illustrated, astandard hydraulic chuckin'g mechanism, 4designated as a whole at 58 isemployed, but as this mechanism is of known construction andforms nopart of the present invention, it will not further be described here.

Mounted on the column 32 of the machine is l a motor 60 (Flgs.'l, 2, and7). This motor drives the carrier 52 and, during lapping, thereciprocating quill 5|, as will now be described. The motor is-connectedby a' suitable coupling 6| with a meshes with a worm wheelkeyed to a shaft 65.

shaft 62 carrying the worm 53. This worm 68 The shaft 85 is journaled onanti-friction bearingsv 68 and 61 in a bracket 13 which is secured tothe column 32.

Splined to the shaft 85 are a pair of" spur change-gears '68 and 69.These are secured against a shoulder formed on the shaft by the nut 10,`which threads on the shaft, .and by the washers 1| and 12. V

'I'hespur-gears 68 and 88 mesh, respectively, with spur-gears 14- and 15(Fig. '7) which have splined connections, respectively, with the shafts.iournaled on anti-friction As this chucking mechanism e4 (Fig. s) thatis..

16 and 11. The gears 14 and 15 are held ontheir respective shafts bynuts' 18 and 19, respectively,

which thread on the shafts and by the washers which cooperate with thesenuts.

` The shaft 16 is journaled on anti-friction bear- 5 ings and 8| in thebracket 13. -The shaft 11 is bearings 82 'and 83 in the bracket 13.'I'here is a spur gear 84 These gears are adapted to be mashedselective.,l

with a spur gear 8 1; (Figs. 7 and 8) that is inte- 88. This sleeve ismounted to 90 .that is journaled on antigral ,with a sleeve slide upon ashaft frictiorrbearings 9| in the bracket 13 and on anti- 15 frictionbearings 9 2 in an arm 94 that is secured to the bracket 13 by screws85.

The shaft 30 has a'worm 96 with it that meshes with a worm-wheel 91(Figs.

8 and '7). 'I'he worm-wheel 91 is keyed to a 20 .sleeve 88 whichforms-'a bearing for a slidable shaft 99. There are two pins |00 and |02secured in the worm-wheel Y31 to project from one side thereof.

Pivotany mounted at los inthe brackems is 25 a yoke-member |05 having aldng arm |03 and a' short arm |04. In .the rotation of the wormwheel,the pin |00 isidapted to. engage the long arm |03 of the yoke-member andh pin |02 is v adapted to engage the short arm |04 of said yoke- 30member, thereby shifting ithe yoke-member alternately in oppositedirections about its pivot |06. 'I'he yoke-member carries opposedrollers vlill which engagev in a recess or groove |08 formed betweentheshoulders |09 and I|0 of the 35 sleeve 88. Thus, as the worm-wheel 91rotates,

-the yoke-member |05 is rocked ilrst in one direction and then in theother'about its pivot |06 to engage the gear 81 alternately with thegear 85 (Fig. '7) and-with the' gear 84. The gears 84' 46 and drive thegear 81 in the same direction so thatthe worm-wheel 81 is driven inthesame direction regardless of whether the gear 81 is -engaged with thegear 85 or the gear 84, but the worm-wheel 911s driven at one rate whenthe 45 gear 84 is driving the gear 81 and at a diierent rate when thegear 85 is driving the gear 81.

The external groove |08l in the sleeve 88- is wider than the'rollers|01, which operate therein, for a purpose which will appear hereinafter.50

'I'ol insure quick shifting of the'yoke-mem'ber |05 and to insure thatthe gear 81 remains in contact with either the gear 84 or 85, which haspreviously been-driving it. until the yoke-member has been shifted sothat there will be a continu- 55 ous drive to the worm-wheel 91 at 'alltimes, av

loadand -fire mechanism and a drag-detent are provided.

.The yoke-member |05"is `operated by a load and re mechanism comprisinga plunger ||5f60 that is housed in a bore in the bracket 13. Thisplunger is spring-pressed outwardly by"a coil spring ||6 and it has aV-shaped outer end orhead 8 vwhich engages the V-shaped head H0 of astud ||1 that is secured in the yoke-member 65 |05. As soon as theyoke-member 805 is rocked past center in either direction', this loadand fire mechanism operates to swing it on quickly and positively to theendof its movement.

The bore of the` sleeve 88 is formed with two 70 conical recesses orgrooves |20 and |2|. The shaft 80 has a hole |22 drilled diametricallythrough it. yThere is a pin |23 mounted in this hole that has a conicalhead |24. 'A sleeve |25 telescbpes on the-pin |23 and thishas a conicalhead |26. 75

keyed to the shaft 16 and there is a spur gear 85 keyed to the shaft 1110 formed integral The two headed members are adapted to en' gage in therecesses |26 or |2| depending upon the axial position of the sleeve 68and they are .pressed apart and into engagement withthese recesses by acoil spring |21. The headsl24 and |26 are pressed by the spring |21 intoengagement with one or the other of the recesses |26 As above described,the external groove |68 inv y the sleeve 88 vis wider than the pins |01which operate therein. Hence, during the rst part 'of the movement ofthe yoke-member l|55 in either direction, no ymovement is imparted tothe sleeve 88 4and gear 81 and it is not until after the yoke-member haspassed center and is being thrown on to the end of its movement by thespring pressed plunger ||5 thatv the sleeve 88 and gear 81 start tomove. The double headed plunger |24-I25 serves to hold the gear 31 inengagement with whichever of the gears B4 o1; 35 that has been drivingit, until the' yoke has passed center. Then the momentum of the'yokeunder actuation of the spring-pressed plunger 5 is sufficient toovercome the frictional resistance of the drag-detent |24|25 and thesleeve 88 is moved on into its new axial position. The drag-detentserves to insure that the gear 81 remains in driving engagement thleither the gear 84 or 85 until movement of he yoke on to its newposition is insured. Thus assurance is had of a drive at all times tothe worm-wheel 91.

The shaft 99 is slidably mounted in the sleeve 98 and in a plain-bearing|36 which is secured in a plate that is secured in 'any suitable mannerAto one side of the column 32. y Keyed to the shaft is a disc ISI onwhose hub is mounted a cam |32 which is secured to the disc |3| byscrews |33. 'Ihe periphery oi? the disc |3| is.

concentric with the axis of the shaft 99. The

' cam |32 may be of anysuitable shape, one typical form of such cambeing shown in Fig. 15.

|35 denotes a roller whichl is mounted upon a stud |36 which is threadedinto a cylindrical bar |38. The bar |36 is adapted to slide 'in atubular guide formed in a bracket |39, which is-se cured to the plate|46 that is secured to the column 32. Either the cam |32 `or the disc|36 may be engaged with vthe roller |35 by shifting the shaft 99axially. burnishing the l'cam is engage with the roller while duringtesting the disc is engaged with the roller as will hereinafter appear.

Mounted in the bar |38`at the end opposite that which carries the roller|35, is a stud |42 on which is mounted a roller |43. 'Ihe roller |43engages one end of a contact-member vor stud |44, that is adjustablymounted in the arm |45 of alyoke-member |46 (Figs. 6, 3 and 4). The yokemember |46 takes its bearing on the periphery of the carrier 52 and issecured to the carrier 52 in any suitable manner to transmit motion tothe carrier.

The contact-member |44 is. held in engage- Y mentwith the roller |43 ofthe bar |38 and the .roller |35 of this bar is in turn held in engager`ment with the cam |32 by a spring (not shown) which operates to urge thecarrier in one direction about its axis. the same as shown in theBullock et al. patent -above mentioned. The contact member |44 isadjusted axiallyin the arm |45 by rotationof ng lapping or .f

The construction may bbethe handwheel |41 which is secured to a shaft|48 that threads into the arm and that abuts at its inner end againstthe opposed end face of the contact member |44. lThe extremity of thearm |45 is in the form of a Split clamp and -fthe contact member may besecured in any adjusted position in the arm by vtightemmg the clampinglever |49.

Fr'om the above description it will be seen that when the cam' |32 isengaged vwith the roller |35 and the shaft 99 is rotated. the cam |32will impart a reciprocating movement to' thebar |38 to oscillate thecarrier 52 on its axis, "thereby causing the gear to be swung about anaxis eccentric of its own axis. Of course, when the disc |3| is .engagedwith the roller |35, the car,-

rier will remain stationary despite the rotation of shaft 99 because thediscis concentric of the shaft.

. The disc or cam selectively is brought into engagement with the roller|35 by moving the shaft 95 axially. Axial movement of .the shaft iseffected by movement of a lever |53 which is plvotally mounted at |51 onthe column 32. This lever is formed at its short end with a yoke portionhaving pins |59 which engage in a peripheral recess formed in theshaft99.

To insure that a cam |32 is engaged with the roller |35 when a pair ofgears are to be lapped or burnished and4 that the disc |3| is engagedwith the roller when a pair of gears are to be tested, a safety deviceis provided. This comprises a double-throw switch |96 (Figs. '7 and 25)which is mounted onf the column 32 in such position that the roller |91,carried by its arm |98 is engaged by one of\the pins |59 of the lever|53 to rock the switch arm when the Shaft 99 is shifted in eitherdirection. The function of this switch Will be described moreparticularly hereinafter.

Keyed to the shaft 99 at one end thereof is a sleeve |56 (Figure 7).'I'his sleeve is journaled on anti-friction bearings |5| and |52 in theendcap |54 of the bracket |39. Secured to the flange |55 of the sleeve|56 by screws |56 is a cam |5E3.

This cam.l may be of any suitable conformation.'

One typical form of such vcam is shown in Fig. 16.

'I'he cam |56 is adapted to engage a roller |63A which is rotatablymounted upon a stud, |6| The stud |5| is secured in one end of Aacylindrical bar |62 which is slidable in a cylindrical 4guide formed inthe bracket |39 parallel to the guide in which the bar |38 slides.

This bar |62 is of reduced dimension at itsl outer end and engages thehalf-round endof a contact member or follower |64 which is rotat'operative., In this position its tip. will engage the surface of the arm|66 which is securedto `the bracket |39'(Fig. 7) by screws |61.

'I'he contact member |64 is held in either position of its adjustment byset-screws |68 and |69 which are adapted to engage in longitudinalgrooves |10 and formed in the contact-member. 'I'he contact member isheld against axial movement relative to the sleeve |63 by the nut |12which is threaded on the outerend of the reduced stud portion of thecontact member.

'I'he arm |65 is p ivotallymounted at |14 (Fig. 5) in a guard |16 andhas a'depending portion (Fig. 3) which is keyed to a screw shaft v| 15which is journaled in suitable bearings in the head 46 and in the guard|16. 'I'he guard |16 is secured to the head. The screw shaft |15 has athreaded portion |11 which engages in a nut |18. This nut |18 is securedin a ring |19 which is rigidly held between the inner end of the quilland a@ spacer member |88 that is secured to the sleeve or quill byscrews, |82. The spacer member |88 is also held against axial movementrelative to the quill 5| bythe sleeve |84 which is keyed to spindle 48and which is formed with. a iiange |85 that engages in a circular recessformed in the spacer member |88. The sleeve |84 is heldin position -bythe brake-drum |86 which is secured on the spindle 48 against axialmovement relative thereto by the nut. |81 that threads onto the spindle.

From the preceding description, it will be apparent that as the camshaft 99 rotates, the cam |58 (Fig. 7) will impart a reciprocatingmovement to the bar |62 and this in turn will oscillatethe arm |65 andscrew |11 to move the quill 5| axially to and fro in the carrier 52,lthereby imparting an axial reciprocating movement toy the spindle 48and the gear G mounted thereon.

A'I'he key |98 (Fig. 3) which is secured to they,

quill' 5I by the screws |9| and thedowel |92 serves to transmit theoscillatory motion of .the-

carrier 52 to the quill 5| andspindle 48 as the spindle rotates and thequill moves axially. y The recess |94 in the carrier in which the key|98 engages is longer than the key to permit free axial movement of thequill in the carrier while maintaining the oscillating drivingengagement between the two.

Coil-springs |95 are provided to take up back- "lashin the screwl |18and yto urge the quill A5| continuously rearwardly in' the carrier 52.'I'hese springs, which are provided at angularly spaced intervals aroundthe carrier, are mounted in aligned openings in the quill and carrierand bear at one .end against the spacermember |88 and at their oppositeends against the carrier,

Thecontact-member |84 (Figs. 5, 6, and '7) is held against one end ofthe bar |62 and the roller |68 is held in contact with` the periphery ofthe cam |58 by action of the spring-pressed plunger |96V (Fig-5). Thisplunger is housed in a bore in the Vguard |18. It engages a roller |91that is secured by a stud |98 to the arm |65. A'c'oilspring |99 housedwithin a bore of the plunger |96 actuates the plunger.

In 'addition to the cams I32fand |58, there are a pair of cams 288 and28| carried by the cam shaft 99. The cam 28 |4 is keyed to the cam shaftby the same keyi'wh-ich serves to secure the disc |3| to the cam shaft(Fig. 7) and the cam 288 is pinned to the cam 28I`. The disc |3| and the1 cams 28| and 288 areheld against axial movement on theshaft by the nut283 which threads onto the shaft. The cam 288 operates' a doublethrowswitch which controls thev direction of rotation of'the gears beingburnished', lapped or tested and the cam 28| controlsasingle throwswitch that eiects the stopping of the machine at the end of theburnishing, lapping or testing .operation The double throw switch isshown in Fig. 17 and the single throw switch in Fig 18.

'I'he double throw switch comprises a body portion 285 and a pair ofblade-arms 286 and 281 that are pivotally mounted at 288 on the bodyportion 285. The body portion 285 is itselir pivotally mnunted upon apin284 in a 'switch-housing 289 which is suitably mounted on the bracket|39. There is a bar 2|6 mounted on the bladearm 286 and this arm carriesa pairv oi' contact points 2|8 and 2H (Figs. 17'and 7). There is a bar2|8 mounted on the blade-arm 281 and this bar carries a pair of contactpoints 2|2 and 2|3. A plunger 2|4 is slidably mounted in the bodylportion 285 'of the switch. A coil-spring 2|5, which is interposedbetween the plunger 2|4 and the blade-arm 286, serves to urge theplunger 2 I4 downwardly and outwardly ofthe body portion 285 and alsoserves to urge the contact points 2|8 and 2H towards contactingengagement with a pair of terminals 2| 1. A coil-spring 2|9 which isinterposed between the body portion 285 of the switch and the .blade arm281 serves to urge the contact points 2|2 and ZIB into contactengagement with the terminals 228.

The body portion 285 of the switch is urged in one direction about,` itspivot 284 by a springpressed plunger 222 which is pivotally connected,at 223 to the body portion'285 of the switch. This plunger is housedand slides in an opening 228 in the end plate 225 which is secured` tothe bracket |39. The coil-spring 228 which surrounds the reduced stemportion of the plunger 222 and is housed in the opening 225 serves toactuate the plunger.

The double blade switch is tripped by la. spring pressed plunger 238which is mounted to slide in an opening 232 in the end plate 225. A coilspring 233 is housed in this opening 232 and surrounds the stem of theplunger 238. This spring is interposed between a shoulder formed on theplunger and a guide-plate 235 which is secured in any suitable manner tothe end plate 225.

There is a teat 238 formed on the projecting portionmf the plunger 238at one side thereof.

The tip of the plunger 2| 4 is beveled off and the 233 forces theplunger outwardly butbecause of the engagement of the teat 238 with theplunger 2|8, this outward movement of the plunger 238 rocks the bodyportion 285 of the switch about the causing the blade arm 286 to breakcontact with the terminals 2|'1 andthe 'blade-arm 281 to make contactwith the terminals 228.

4The terminals 2|1, as will hereinafter appear, are in the circuit ofthe main-drive motor 48, which drives the gears being burnished, lappedor tested, when the gears are rotating .in the lforward direction andthe terminals 228 are in the circuit of the motor when the gears arebeing driven in the reverse direction.

After plunger 238 has rocked the switch 285 to break contact with theterminals 2|1 and make l -'contact with terminals 228, the plungercontinues to move outwardly under 'actuation of the spring 233 .untilthe`teat 236 rides clearl of the plunger 2|8. Then, of course theplunger222 and spring 226 will rock the switch back in the opposite directionAto break contact at the terminals 228 and make contact again with theterminals 2W.

To insure that'the contact points 2|2 and 293 will make contact with"the terminals 220 long enough to insure starting of the drive motor inthe reversed direction, the end of the plunger 288 is formed withashoulder 248 andthe tip of the 75 50 pivot end 284 in avcounter-clockwise direction,

lug or cam 266e is beveled Voii? as indicated at 242. As the cam' shaft98 rotates, then, the cam rst engages the end of the plunger- 288pushing the plunger far enough in to engage the teat 286 behind theplunger 21d. rotation of the cam shaft, the cam 280 rides clear of theend of the plunger and allows the plunger to move outwardly underactuation o"the spring 233 causing the switch to break contact with theterminals 2| 1 and make contact with the terminals 220 but when the cam288 rides clear of the end of the plunger 238, it engages the shoulder266 of the plunger and the )outward movement of the plunger underactuation of the spring 238 is halted. 'Ihe beveled portion 252 of thecam engages theA shoulder 250 of the plunger for a long enough intervalto assure that the reverse drive is started. Then the bevel portion 252of the cam 280 rides clear of the shoulder 2&8 of the plunger and theplunger completes its movement to the right under actuation of thespring 233, breaking contact at the terminals 228 and making contact'again at the terminals 2 i 1 in the manner already described.

The single blade switch which controls the stopping of the machinecomprises a body portion 255 and a blade-arm 248 which is pivotallymounted atv 251 on the body portion 255. The body portion 255 ispivotally mounted upon a pin 248 in the switch box 268. The switch armcarries a bar. 258`which is provided with contact points 252 and 253(Figs. 7 and 18) that are adapted to make contact with terminals 255(Figs. 18 and 25). v When contact oi the points 252 and 258 vith theterminalsV 254 is broken, the machine s Ops.

There is a spring pressed plunger 256 slidably mounted in the bodyportion 245 ofthe switch. A coil spring 258 is interposed between theplunger 256 and blade-arm 246 and serves to urge the plunger downwardlyand outwardly and the blade-arm upwardly into Aoperative position. Aspring pressed plunger 268 is pivoted to the body portion 245 of theswitchat 26|. This plunger is housed land slides in an opening 262 inthe end plate 225 and is pressed' upwardly by the coil spring 263 whichsurrounds the stem on the plunger. i wardly to normally rock the bodyportion 245 olf th switch about its pivot 248 to hold the switch c oseThe body portion 245 of the switch is rocked in a counter-clockwisedirection 'to open the switch by operation of a spring pressed plunger265. This plunger is housed in an opening in the end plate` 225 andslides therein. It is pressed outwardly by a. coil spring 266 whichsurrounds the stem ofthe plunger and is interposed between a shoulder onthe plungerand a cap-plate 261 which is secured to the cover plate 225.

There is a teat 268' formed on one side of the plunger 265 near theouter end thereof. This teat has a beveled end. When the cam 20| engagesthe plunger 265 in the rotation of the cam shaft 98, the lplunger isforced inwardly against the resistance of the spring 266 and the teat268 rides under the plunger 256 which has a beveled tip complementary tothe beveledtip of the teat. When the cam 20| has rotated clear ofthe endvoi the plunger, the spring 2 68 forces thel plunger outwardly again'but at this time the teatf268 is engaged behind the plunger 256 and sothe switch is rocked about its pivot 248 causing the contact points 252'and 258 to be dis-engaged from the terminals 264. This opens the 'I'henin the continued This spring presses the plunger upcircuit of themachine as will be described morel particularly hereinafter, and stopsthe machine. As the plunger 265 continues to move outwardly underactuation of the spring 266, the teat' 268 clears vthe plunger 256 andthe spring pressed 5 plunger 260 operates again to close the switch.

A dash-pot is provided in conjunction with the .plunger 268 so as toprevent the switch being closed again before the circuit to thecontrollers of the machine has actually been broken. This 10dash-potcomprises a plate 218 (Fig. 18) which is secured between ashoulder on the stem of the plunger and the nut 21|. 'I'he plate 210slides in a chamber or recess 212 and has substantially air-tightengagement with the walls of this 15 chamber. There are holes 213through'the plate. Above the plate there is a disc 215 slidably mountedon the stem of the plunger and. having'a llmited movement thereon. Whenthe plunger 260 .moves downwardly on the opening of the switch, 20

air passes freely through the openings 213 in the plate 218 and themovement of the plunger is not restrictedbut when the plunger mores up.-wardly again to reclose the switch, the disc 216 rests on the top of theplate 218closing the open 25 ings 213 and air is entrapped between theplate 218 and the inner' end` wall of the chamber 212 and so the upwardmovement of the plunger is retarded preventing re-closing of the switchun til suicient time has elapsed Ifor the controller to function andactually stop the machine.

To prevent the lapping or burnishing compound irom being sprayed aboutand to protect the operator against injury during burnishing or lappinga guard is provided to enclose the gears 35 during the burnishing orlapping operations. This guard comprises a xed housing 280` (Figs.

1 and 13) and a door or closure 282 that is pivotally mounted on thehousing 288. The xed i housing 280 is secured to the base 38 of the ma-40 chinev in any suitable manner in position to enclose the gear andpinionbeing burnished or lapped as shownin Fig. 2. 'Ihe door 282.permits of access to thegears, removal of the gears after theuburnishing or lapping operation has 45 been completed and chucking ofgears for a new operation. The door 282 is pivotally mounted uponthe xedhousing 288 by means of a pin orl bolt 283. Y A coil. spring 284, whichsurrounds this bolt, has 50 one end in engagement withthe door and theother end in vengagement with the xed housing and serves to hold thedoor in any position to which itis moved. A handle 285 is secured to thedoor at one sidethereof to permit easy manipula- 55 tion of the door. yl

'I'he lapping compound is pumped ontopthe gears by a pump shown indotted lines in Fig. 1 which is driven by a motor 285'. The pump fforces the lapping compound through the line 60 281 (Fig. 13) and thepipes 288 and 28,8, which are secured in the housing 280 into an elbowA288 (Figsl 13 and 14). T he elbow '286 has one or more openings 292 init through which the lapping compound may drop into a funnel-shaped c5receptacle 288. This receptacle is secured by screws 284 to the door 282and it has a flexible hose 295 connected to it and leading from it; ThenozzleA 298 of this exible hose is held in abracket 1 291 that isvertically and horizontally adjustable 70 upona second bracket 298which' is ho ntally adjustable uponv'aI supporting 'plate )2 9. Thesupporting plate 288 is clamped to ribs 388 formed on the door 282 byclamping-.gibs 882 and screws 388 andthe supporting'plate ishorizontally yad- 75 minnie justable on the ribs 300 in a direction atright angles to the direction of adjustment of the bracket 298 on thesupporting plate 209.

The bracket 2914 is secured to the bracket 208 in any position of itsadjustment thereon by the bolt 304 which passes through the verticalslot 305 in the bracket 291 and the horizontal slot 306 in the bracket298. The bracket 298 is secured to the supporting plate 239 in anyposition of its adjustment thereon by bolts 308 which pass throughhorizontal slots 309 in a projecting portion 3|0 of the supportingplate.

'I'he various adjustments described permit of directing the lappingcompound, when the door 282 is closed, onto the gears being lapped atthe most desirable point for the lapping process.

The portion of lapping compound pumped up by the pump and which does notflow out through the opening 202 flows on through the elbow 290 into areturn pipe 3| 5 which carries the compound past the gears and allows itto drop into the bottom ofthe fixed guard 230 whence it is returned tothe sump of the pump system by the return pipe? The pipe 280 isordinarily being operated for a lapping or burnishing process withoutthe' door 282 being closed, a double-throw limit switch 320 is mountedon the fixed housing 280. This switch is so mounted that the roller 32|carried by its switch arm 322 must be engaged by the flange of the door282 to close the switch before the motors 40 and 60, which drive thegears and eilect the burnishing or lapping motions, respectively, can bestarted vas will be described more' in detail hereinafter.

For applying a load to the gears during testing, a standard hand-brakemay be employed such as illustrated in the patent to Slade No. 1,796,484above mentioned. It is manipulated by the lever 325 (Fig. 2). This brakewill operate upon the brake-drum |84 (Fig. 3) but as the construction ofthe same forms no part of the present invening or lapping operation. Animproved form of back-lash brake has been provided upon the pres-v entmachine and this will now be described. 330` (Figs. 9 and 10), denotes ahousing or sump which is secured to the end or cover plate 332 of thehand brake mechanism (Fig. 3) by bolts 334 (Fig. 10). The end plate 332is secured to the guard 335 of the hand brake mechanism by screws 336which thread into lugs formed integral with this guard. The guard issecured to the spacermember by screws '338 which pass through lugs inthe guard and thread into the spacermember. The cylinder 33| whichhouses the chuck-releasel iston 58 is secured to the housingn 330 byscrews 333.y

A gear pump 340 of any usual or suitable cor.- struction is mounted upona bracket 34| which is secured by screws 342 to the'housing 330 at oneside thereof. The pump 340 is driven from the gear spindle 48 through apulley 331 which is fastened to the spindle, a pulley 339 which isfastened to the motor shaft of the pump, and the belting 343 whichconnects the two pulleys.

Flexible hose 344 and 345 are connected to opposite sides of the pump.The hose 344 is connected by an elbow 346 with a duct 341 formed in onewall of the casing 330.' The duct 341 connects with a well 348 formed inthe bottom of the casing 330 (Figs. 9 and 11). There are two parallelducts 349 and 350 that lead downwardly from this well. The duct 349communicates with a duct 35| which is normally closed by a relief valve353. This relief valve is slidable in the duct 35| and in alignedopenings formed in the bottom of the casing 330. It is normally held inclosed position by a coll spring 354, the tension of which may beadjusted by the screw 355 whichvis operated by the hand wheel 3,55.

The valve 353 has openings 358 therein which permit liquid to flow fromthe ductl 35| into the sump 360 when the valve is forced open bypressure of oil flowing into the'duct 35i through the line 344 from `theexhaust side of the pump 340. When the line 344 is on exhaust, the duct350 is closed by a ball check valve 33| that shuts off communicationbetween the duct 350 and a duct 362 which leads into the sump. When thepump 340 is rotating in theoppeosite direction, however, and the line344 is on suction, the valve 33| is open and oil is drawn from the sump330 into the pump. y

The hose 345 connects with a duct 333 which is similar to the duct 341and this duct connects with a well which is similar to the well 348 andfrom which there lead two ducts similar, respec- .Y tension of therelief valve associated. with the line 3451s designated at 335.

When the gear spindle 48 is rotating` in one direction the pump 340 isso driven that it sucks oil from the sump through the ball check valve33|, ducts 350, wdl 348, duct 341, elbow 346 and piping 344 and itexhausts this oil through the piping 345 and duct 363 and `a reliefvalve corresponding to the relief valve 353 back to the sump. In thisvdirection of rotation'` of the spindle, the speed of rotation of thepump and therefore of the spindle is determined by the adjustment ofthe-hand'wheel 365 and of the relief valve controlled thereby. .Henceany desired load may be applied to the spindle 43 when rotating in thedescribed direction.

Whenthe gears and .spindle 48 are rotating fin the opposite direction,oil is sucked from the pump 360 through a ball check valve correspondingtothe ball check valve 33|, the vduct 333 and the line 345 and is1exhausted from the pump through the line 344, duct 341, well 343, duct353, relief valve 353 and the openings'338 inv that valve back to thesump. The rate of rotation of the pump and of .the spindle 48 is thendetermined byy the adjustment of the relief valve 353 through the handvwheel 353.y By the mechanism Y described, then, any suitable lad can beapplied to the spindle 48 and to the gears being bur-A rushed or lappedduring rotation of the gears in either direction. Pressure gauges 313and 313 are provided to permit determining the brake- .load in eitherdirection accurately.

One of the features of the present machine is the incorporation in themeans for adjusting the pinion head 3| of a. dial gauge to permitprecise adjustment of this head so that the pinion P may be adjustedaccurately into correct meshing relation with the gear G for lapping ortesting. The pinion head 3| is adjustable by means of a screw shaft 310(Fig. 12) that threads into a nut 31| which is secured to the pinionhead. The shaft 310 has a. sliding key connection with a sleeve 312 towhich the hand wheel 314 is secured. The pinion head is also movable bymeans of a piston 315 which is connected to a piston rod 315 and isslidable in a cylinder 395 that is secured in any suitable manner to thebase of the machine. The piston rod 316 is connected to a yoke member313 by a nut 311. This yoke member is connected through ball thrustbearings 319 and 380 and the nut 382 to the screw shaft 310.

The piston 315 may be operated by a rotary control valve and an inchingvalve such as described-in Patent No. 1,881,999. As these valves form nopart of the present invention they will not be described here.

Secured in any suitable manner to the yoke member 318 is a plate 385.'I'his plate has a hook 386 at one end. The hook is adapted to engagevlthe short arm of a magnifying bell-crank lever 381 that is pivoted at388 on a guard 389 which is secured to the base or frame 30 oi themachine. The long arm of the bell crank lever 381' engages at its tipwith the contact point of a dial gauge 390 which may be of standard orany suitable construction and which is also mounted in the guard 389. Aglasssight 392 is provided in the guard to permit the operator toreadily read the dial gauge.

For precision lapping or testing, it is desirable i to havev the gearsbeing lapped or tested meshed very accurately as to depth. This is donein the present machine by first finding precisely the bottoming positionof the pinion in the gear, that is, the position in which the tops ofthe pinion teeth bottom in the tooth'spaces of the gear and by thenbacking the pinion outof bottoming position the predetermined distancerequired until the pinion will run with the gear in the desireddepth-wise mesh relation.

To nd the bottoming position of theV pinion,v

the teeth of the gear are aligned with the tooth spaces of thpinion andthe pinion head 3| is inched on to the limit of movement ofthe piston315 in "its cylinder 395 to engage the teeth and tooth spaces of thepair in mesh. The piston in its movement carries the piston rod 316 and.yokemember 318 with it and the yoke member carries the screw shaft 310,sliding this shaft inthe sleeve 312. Just before the piston 315 hasreached its limit position, theV hook 386 on the plate 385 will engagethe short arm of the lever 331 and impart movement to the contact pointof the gauge Y gauge.

pinion teeth actually' Aswitch 245,the line 425;

left. This slight movement will be reected through the magnifying lever381 to the dial gauge and the operator will know immediately that he hasreached bottoming position. The operator will then rotate the hand wheel314 to back the pinion away from the' gear a pre-determined Vdistance tothe point where the pinion and gear will run accurately together,ordinarily to the position where theyhave true pitch-line mesh. In thisbacking-away movement, the head 3| will be moved relative to the piston315, for the shaft 310 will rotate in the nut 31|. The amount of thebacking-away movement may be determined accurately by reading themicrometer dial 396. against a zero mark on the end plate 391 ofthecylinder 395.

Having precisely determined the correct position of mesh of one pair ofgears, the settings of the screw shaft so determined will do for anypair of identical meshing gears and thereafter any pair of identicalgears may be brought into correct depthwise meshing relation simply byinching the piston 315 on to the limit of its movement in its cylinder.lIt is only necessary to make a new precision setting when a differentratio of gears is to be lapped or tested.

For lapping, as has been described, the gear and pinion are rotatedtogether in mesh andsimultaneously the carrier 52 is oscillated toimpart an eccentric motion to the gear and the quill is reciprocated to`impart a depthwise movement tothe gear. For testing, the gears aresimply run together in mesh and the oscillating motion of the carrierand the reciprocating motion, of the quill are'omitted. One way in'which a combination lapping and testing machine may be wired toaccomplish the purposes oi' the present invention is illustrateddiagrammatically in Fig. 25. The lapping circuit will be described rst.

At some convenient point on the machine there are secured an electricstart button 400 and an electric stop button 40| (Fig. 25). The startbutton is a normally open button and the stop button is a normallyclosed button. For lapping, the door 282 (Fig. 13) of the guard 280 mustbeclosed before the machine can be started so that the switch 320 is inthe position shown in` Fig.. 25 with the bar 402 bridging the terminals403 and 404. 'I'he axial position of the shaft 99 must also be such thatthepam |32 (Fig. '1) is inv engagement with the roller |35 so as to beable to' impart the oscillating movement tol the carrier 52. In thisposition of the shaft, the switch |96 will occupy the position shown inFig. 25 with the bar 405`bridging the terminals 401 and 408. Thereversing switch' 205 will be in the position shown in the Figs. 17 and25 with the bar 2|5 and the contact points carried thereby bridging theterminals 2|1. The stop switch 245 will be in the position shown inFigs. 18 and 25 with the bar 250 bridging the terminals 254.

-When the operator presses the starting button 400 a circuit is made'from the main line L1 through the line 4|0, the terminals 403 and 404andthe bar 402, theline 4|2, the line 4|3, the line 4|4, the terminals4|5 and 4|5 and the start- 420, the line 42|, the line 422, theterminals 423 and 424 and the stop button 40|. the line 425,V

the terminals 254 and the bar 250 of the stop 428 and the bar 429 of thereverse controller for the terminals 421and the maindrlve motor 4I ofthe machine, the line 'I6 488, the terminals 431 and 482 and the bar 443of the forward control] r for the motor 48, the line 435, the terminals4 8 and 431 land bar 438 of a controller for the oscillating drive motor68 (Fig.

'7), to the main line L2. This circuit energizes' the coil 428 to closea two-pole normallyr open relay 448.

As soon as the relay 448 is closed, a circuit is made which energizesthev forward and oscillating controllers. The circuit to the forwardcontroller is from the main line L1 through the line \442, the terminals443 and 444 and the bar 445 of therelay 448, the line 448, the-coil 441of the forward controller, the line 448, the line 422, stop button 481-and the lines previously described to the main line L2. The circuit tothe oscillating controller is made from the main line L1 through theline 452, the terminals 453 and 454 and bar 455 of the relay 448, theline 456, coil 451 of the oscillating controller, and lineI 458 to theline 448 and. thence through the line 422 and stop button 481 to`themain line L2 inthe manner already described.

The energized coil 441 pulls the switch-blades 468461, and 462 closed sothat they make con- .tact with the terminals 454, 455 and 465,respectively and close a circuit to the main drive motor '48 (Fig. 1.).through the forward controller and the lines 468, 459, and 418. vThisstarts the motor 48 driving the meshing pinion P andthe gear G in theforward direction. At the same time that the energized coil 441 closesthe switch arms 468, 461 and 452 it also closes-.the switch arm 412.

The energized coil 451 closes the switch arms 415, 416, and 411 and alsothe switch arm 418 so that these arms make contact, respectively, withthe terminals 488, 481, 482, and 483 of the oscillating controller. Theclosed. switch arms 415, 415,

and 411 make a circuit through the oscillating breaks the circuit to thecoil 428. The relay 448 v is a normally open relay. Hence when thecircuit to the coil 428 is broken, the relay 448 opens. This breaks thedescribed circuit to the coils 441 and 451, but the circuit to thesecoils is now maintained through the switches 412 and 418, respec-.-tively, and so the motors 48 and 88 aire not stopped.

The circuit to the coil 44'1 is maintained from the line L1 through theline 418, terminals 484 and 484 and bar 482, line 41 I, terminals 488and 481 and bar 486, line 412, line 498, line 491, terminals 492, switcharm 412, line 494, terminals 211 and bar 215 of switch 285, line 495,line 445, the coil 441, lines 448 and 422, through the stop but- "ton481 and the already described connections to the mainline L2. Thecircuit to the coil 451 is maintained' from the main line L1 through thedescribed connections with the lines 412 and 498, the line 491, terminal483,*switch 418,fline 498, coill 451, lines' 458, 448 and 422 and stopbutton 481 through the already` described connections to the main lineL2.

Thedescribed circuits to the main drive motor 48 and oscillating motor68`are maintained until gaf the cam 288 (Figs. '7 and 18) trips theswitch 285,

l breaking contact of the bar 215 with the terminals 211 and causingcontact to be -made between the bar 218 and the terminals 228.

When contact of the bar 218 with the terminalsi 211I is broken, the coil441 is de-energized; the switch arms 4158, 461, 482, and412 open and themain drive motor 48 stops. As soon as the con-l tact bar 218 makescontact,)however, with the terminals 228, the main drive motor isre-started' l 'but in therevers'e direction. Theclosing of the contactof the bar 218 with the terminals 228 causes a circuit to be made fromthe line L1 through the line 418, the terminals 483, and 484 and bar 482of switch 328, the line 411, terminals 488 and 481 and bar 4116 ofswitch 185, line 41?@line 413,. line 588, terminals 228 and bar 218 ofswitch arm 281, lines 581 and 582, coil 583 of the reverse controllerline 584, Vand lines 448 and 422 through Vthe stop button 481 and thepreviously described connections to the main line La. This energizes thecoil 583 closing the switch blades 585, 585 and 581 and also the switchblade The switch blades 585, 5856, and 581 make contact with theterminals 518, 511, and 5 12, respectively, causing the man1/drive motor4t to be driven in the reverse direction through the lines 514, 515, and515.

As already describedf the nose of the cam 288 contacts with the shoulder248 of the plunger 238 (Fig. 17) only long enough to i ure restarting ofthe drive motor 48 in the reverse direction. -Then the nose of the camslips off of the shoulder of the plunger and` contact of the bar 218 ofthe switch 285 with the terminals 228 is again broken. The circuit tothe coil 583 is maintained, however, from the line L1v through the line418, switch' 328, line 411, switch |85, line 412, line 488, terminal528, switch 588,'coil 583, lines 584, 448, and 422 and stop vbutton 481and connections already described to the main line Le.

'I'he main drive motor 48 continues to drive the pinion P and gear G inthe reverse direction until the cam 281 (Fig; 18) trips the switch 2.45.'Ihen the circuit -to the coils 583 and 451 through the stop button 481is broken and both motors 48 and 88 are stopped. This stops the machinewith its operations completed in one revolution of the cam shaft 89. Thestop switch 245 closes again automatically but its 1re-closing isretarded sufficiently by the dash-pot plate 218 to insure `breaking ofthe circuit to the coils 583 and 451 and opening of theswitch arms 588'and 418. Hence, on the re-closing of the switch 245, the motors 48 and'88 are not restarted, nor can they be restarted until the start button488 is againvpushed in and when the start buttorr488 is y again pushedin, the machine will go through its full cycle. v

In order to use the machine for testing gears, the camshaft 58 must beshifted amally by the lever 153 (Fig. '7) to disengege the cam 132 fromthe roller and bring the concentric disc 151 into engagement with thisvroller for in the testing operation, the gear G and pinion P are runtogether in` ixed positions and neither an oscillating motion nor anaxial mation or' the gear is desired. In testing, also, the door 282 ofthe guard 288 (Figs. 1 and 13) will beopen.

When the cam shaft 841s shifted to engage the roller with the disc 181",'the arm of the switch 198 will be moved to cause the bar 485 of thisswitch to break contact with the terminals 481 and 488 and to cause thebar 525,0f this switch to make contact with the terminals

